246 FEANCIS DAUWIN. 



or not the glands have anything to do with the absorption of the 

 putrescent fluid in the cups of B. sykestris, some other function 

 must also be performed by them in the economy of the plant. 

 Another idea which occurred to me was that the Blaraents might 

 be low organisms of the nature of a Myxomycetes, living para- 

 sitically on the summits of the glands. The reasons for dis- 

 carding this view will be fully given in the sequel. 



The trichomes on the connate leaves of the second year's 

 growth all have the shape of glandular hairs (except a double 

 row of simple multicellular hairs on the midrib) ; the seedlings 

 possess in addition numerous long hairs or prickles, the chief 

 portion of which consists of a single large conical cell, sometimes 

 "85 millimeter in length, and '09 millimeter in breadth at the 

 base. The glandular trichomes are of two kinds, exempli- 

 fied by figs. 1 and ] 3. The trichomes of the fig. 1 type are of no 

 further interest, as they do not produce motile filaments. The 

 other variety (fig. 13 and the other drawings) consist of a pear- 

 shaped multicellular head, about "05 millimeter in length, and a 

 unicellular cylindrical stalk a little over "03 millimeter in length, 

 supported on a cushion-like cell projecting to a variable extent 

 above the level of the epidermis ; the whole trichome is about 

 -i-Jjth millimeter (o^-^^o^th of an inch) in height. In the glands on 

 the second year's leaves the cells forming the pear-shaped head 

 usually contain a few bright spheres of a resinous substance : 

 the latter may be removed by alcohol, and then the nuclei of the 

 cells become clearly visible. These large drops of resin are 

 often absent, especially from the glands of the seedling leaves ; 

 in this case the cells contain merely granular and cloudy pro- 

 toplasm. The drops of resin are, however, sometimes to be 

 found in the seedling's leaf-glands, as shown in fig. 13. Both 

 the trichomes of the fig. 1 type, and also those which prodiice 

 filaments, occasionally contain a good deal of starch. 



The stalk-cell exhibits a simple network of streaming pro- 

 toplasm and a large nucleus. I have once or twice observed 

 streams of protoplasm in the transparent cells forming the pear- 

 shaped head of very young glands. The glands are often capped 

 by accumulations of resinous secretion, and this is more fre- 

 quently the case with the second-year leaves than with the seed- 

 lings. These secreted masses agree with the bright spheres 

 found within the cells in exhibiting the following reactions, 

 which show them both to be of a resinous nature. They are 

 soluble in ether or alcohol, are coloured pink by tincture of 

 alkanet ; they are not blackened by osmic acid, as would be the 

 case with a fatty substance. The crusts on the outside of the 

 glands, contrary to what might be expected, are stained yellow 

 with iodine. It appears, therefore, that the resinous secretion is 



